| Abstract |
Διατμηματικό, συνεργαζόμενα Τμήματα Χημείας του Πανεπιστημίου Κρήτης και Χημείας του Πανεπιστημίου Αθηνών. The present thesis is dealing with the study of a new method for the synthesis of linear 3,5-dienoic esters and their derivatives, and the determination of the stereochemistry of this conjugated dienoic system. Such compounds have been isolated and identified as volatile components of fruits and flowers as well as major components of insects pheromones. The synthesis was performed by applying the Ragoussis method, (which is a variant of the typical Knoevenagel for the synthesis of 3-unsaturated esters) on n-2-E-unsaturared aldehydes with monoethyl malonate, using DMSO as a solvent and piperidinium acetate as a catalyst. The method was applied to the following aldehydes: E-2-hexenal, E-2-octenal, E-2-decenal and E-2-dodecenal. In all cases, the product was a mixture of the (3E,5Z), (3E,5E) and (2E,4E) dienoic esters geometric isomers, in an approximate 37:45:18 ratio. In order to obtain pure products and study the stereochemistry of the dienoic system we used a) Column Chromatography and b) Selective formation of complexes between the geometric isomers and urea-methanol. E,E esters were selectively encaged in the urea channel, whereas the 3E,5Z remained in the filtrate thus leading to satisfactory results. In this way, it became feasible to isolate 3E,5Z dienoic esters in a relative high purity (92-95%). The overall yield concerning the pure 3E,5Z-isomer was 20-30%. Further treatment of the above mentioned esters, led to products that are the major components of sex pheromones from Lepidoptera and Coleoptera insects. These products are: · (3E,5Z)-3,5-dodecadienyl acetate (3E,5Z)-3,5-dodecadienyl acetate is a major component of the sex pheromone of the leaf-roller moth Phtheochroa cranaodes. · (3E,5Z)-3,5-tetradecadienyl acetate (3E,5Z)-3,5-tetradecadienyl acetate is a major component of the sex attractant pheromone of the moth Recurvaria leucatella. · (3E,5Z)-3,5-tetradecadienoic acid (3E,5Z)-3,5-tetradecadienoic acid is the sex attractant pheromone of black carpet beetle Attagenus megatoma. The Verley-Doebner reaction of 2-E-aldehydes with monoethyl malonate in the presence of pyridine and DMAP as a base, was also studied in this work. The major products obtained in this reactions were the 2,4 (E,E) and (E,Z) esters, and in a lesser extent the 3,5 (E,E) and (E,Z). Complex formation with urea did not lead to complete separation of these dienic geometric isomers, but to (2E,4E) and (3E,5E) mixtures, which were not further separated.
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Α. Μελέτη τροποποιημένης συμπύκνωσης Knoevenagel σε Ε-2 ακόρεστες αλδεΰδες. Β. Εφαρμογή στη σύνθεση φερομονών
